Benomyl is a widely used fungicide which has been effective worldwide against many diseases of commercially important crops. However, the repeated use of benomyl has resulted in the selection of benomyl resistant fungal isolates against which benomyl has significantly reduced activity, thereby necessitating the use of alternative and often less effective fungicides.
There has been considerable research in the field of fungicides in an attempt to locate a fungicide which is not only effective against the fungal isolates which are benomyl resistant, but also effective against fungi which are sensitive to benomyl. As reported by G. P. Clemons and H. G. Sisler in Pesticide Biochemistry and Physiology, Volume 1, pp. 32-43, 1970, it was believed that benomyl degrades to methyl 2-benzimidazolecarbamate which was thought to be the effective ingredient of the fungicide. As a result, most research has been directed at locating other types of fungicides which would be effective against the benomyl resistant fungal isolates. However, this research has not led to any significant fungicide which is useful in this area.
Benomyl has the chemical formula, methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamateis as disclosed in Canadian Pat. No. 820,317. The fungicidal properties of benomyl and other types of methyl-2-benzimidazolecarbamates are disclosed as being useful as fungicides. However, since it was generally understood that benomyl degraded rapidly to methyl-2-benzimidazolecarbamate (BMC), there have been no investigations to determine if any of the other related compounds disclosed in this patent specification would have any effect on benomyl resistant fungal isolates.